In the Begg Technique, factors controlling the anterior intrusive force provided by the archwire have yet to be fully clarified. The rationale for bite opening with very light forces, the effect of Class H elastics on intrusive force magnitude and the intrinsic quality of 'Australian' wire in bite opening are examined in this paper. A formula is presented which allows the intrusive force that archwires exert in different individuals to be predicted. The values derived from the formula were compared with case model measurements. It was found that the intrusive force of the archwire was affected by the length of the individual dental arch. The magnitude of this intrusive force was seen to increase gradually during the period of bite opening and appeared to be related to the use of Class H elastics. The study revealed factors which affected the magnitude of the intrusive force.

A patient with skeletal Class Ⅲ malocclusion was treated in 2 phases during the early permanent dentition. In phase 1, maxillary protraction was combined with rapid palatal expansion; in phase 2, fixed appliances were placed. The results were good posttreatment, and, 1 year later, a favorable growth tendency could be observed. This report shows that treatment for a patient with skeletal Class Ⅲ malocclusion can be started in the early permanent dentition, with very good final results.

The purpose of this study was to evaluate dentoskeletal and soft-tissue profile changes after extraction of lower second molars and treatment using the Tip-Edge technique in severe Class Ⅲ subjects. Thirteen patients with severe skeletal Class Ⅲ malocclusion (four males, nine females), diagnosed as requiring orthognathic surgery, but who rejected surgical therapy, were included in the study. The average age was 13.2±0.8 years. Lateral cephalometric films taken at the beginning and the end of treatment were analyzed using the Pancherz analysis and a traditional cephalometric analysis. The arithmetic mean and standard deviation were calculated for each variable. Paired ttest was performed to evaluate significant treatment change. After active treatment, dramatic overjet change was noted, with an average value of 5.5mm (P>001). Inclination of lower incisors was decreased 12.08 when measured to the mandibular plane (P>001). Inclination of upper incisors was increased by 2.18 to the SN plane (P<05). A negative value of the distance between upper and lower lip position to Sn-Pg9 at the beginning of treatment changed to a positive value (P<001). The results of this preliminary study suggest that success in the treatment of some severe Class Ⅲ deformity in the permanent dentition can be achieved with fixed appliances and extraction of lower second molars. A remarkable soft-tissue change was noted after the treatment, and concave facial profiles changed to straight profiles.

Summary. In this retrospective cephalometric study, the lateral skull radiographs of 12 children with Class III malocclusions of skeletal origin were examined. An analysis ofthe changes produced during treatment revealed that whilst changes in apical base relationship were small, and were mainly limited to a reduction in angle SNB, the effects on the soft tissue profile were surprisingly effective.

Environmental improvements can lead to greater size of skeletodental structures as the population comes closer to expressing its genetic growth potential. Such secular trends have been documented in many human settings, especially for increased stature and faster tempos of growth. The present study is based on 185 same-sex parent-offspring pairs of data for maximum buccolingual crown diameters of the permanent teeth from a cohort in Beijing, China, where parents experienced much of their development during and after World War Ⅱ with the deprivations of the changing regime. Their offspring enjoyed the relative stability of the established Communist system, where nutrition and stability were much improved. There were significant increases in buccolingual diameters of the premolars and molars in the offspring. Increase for premolars and molars was about 1%, but larger in females than males (1.6% vs. 0.5%). Opposite changes occurred in the incisors and canines (i.e., larger parental dimensions), but we contend that these are an age-related artifact brought on by greater passive eruption of older individuals' teeth that exposes a broader portion of the crown at the gingival margin. The secular trend in crown size coincides with other research in contemporary China, disclosing increases in body size and faster tempos of growth as health and nutrition continue to improve.